Operator's Manual: Radio Set AN/GRC-26D. 1969-06-19 "This manual describes Radio Set AN/GRC-26D (fig. 1-1) and covers its installation, operation, and operator’s maintenance. It includes operation under usual conditions, as well as operation with security equipment; cleaning and inspection of equipment; and replacement of the parts available to the operator. Detailed discussion of Modulator, Radio MD239(*)/GR; Switch Box SA-331/U; Control, Radio Set C-1123/GRC; and Control, Remote Switching C1474/GRC is provided. Detailed information pertaining to the remainder of the major components comprising Radio Set AN/GRC-26D is contained in the technical manuals listed in appendix."